1. Field of the Invention
The present invention relates to a probe apparatus and probe testing method for testing the electrical characteristic of a plurality of to-be-tested objects (hereinafter referred to as “chips”) provided on a substrate (hereinafter referred to as a “wafer”) W. More particularly, it relates to a probe apparatus that includes detection means for directly detecting the position of each chip and the position of a probe card, and a probe testing method.
2. Description of the Related Art
To detect the position of a chip, it is necessary to align the X-, Y-, Z- and θ-directional positions of the probes of a probe card with those of the chip, and to raise the chip toward the probes to bring it into accurate contact with the probes with a predetermined overdrive amount. To this end, it is necessary to accurately detect the position of the chip. Since the foundation layers of the electrode sections or electrodes of recent chips are thin and soft, excessive overdrive may damage, expose and/or crack the foundation layers. To achieve such alignment, each electrode of a chip and the tip of each probe have been photographed by a camera to detect their positions. The detection of the X-, Y-, Z- and θ-directional positions using a camera can be performed highly accurately, and is therefore widely utilized. However, in Z-directional positioning using a camera, the camera is focused on a target, and the distance therebetween is measured. Accordingly, this method is disadvantageous, for example, in that the range of distances that can be measured is narrow, and the detection accuracy is low. A detection error, if there is any, adversely influences the contact pressure between the probes and the chip. As a result, the probes and chip may be damaged, or the probes may not satisfactorily contact the chip to cause a characteristic detection error. Jpn. Pat. Appln. KOKAI Publication No. 11-26524 discloses an apparatus for performing Z-directional positioning of probes and a chip using optical length-measuring units. Although the apparatus disclosed in this publication has two optical length-measuring units, it cannot directly detect the positions of the probes and the chip. Further, it is necessary to move a main chuck to a predetermined position for position detection. It is also necessary to perform focusing of a camera during position detection, and to measure the distance between the probes and the chip from the focal point. Therefore, much time is required for position detection, and accurate position detection cannot be achieved.